Arylsulfonic acid bromophenyl esters, their preparation, and their use as flameproofing agents

ABSTRACT

Aryl sulfonic acid esters of the formula ##STR1## wherein R 1  represents hydrogen, alkyl groups of 1 to 8 carbon atoms, bromine or chlorine, R 2  represents R 1  or the group ##STR2## Hal represents bromine or chlorine, x the numbers 2 to 4, n the numbers 3 to 5, y the numbers 4-x; m=5-n, R 3  represents bromine, chlorine or the group ##STR3## and Z represents --O--, --S--, ##STR4## alkylene with 1 to 4 carbon atoms, or alkylidene; a process for their product and their use as a flame retardant, especially for polyolefins.

This is a continuation of application Ser. No. 660,953 filed Feb. 24,1976, now abandoned.

BACKGROUND

The invention relates to new arylsulfonic acid bromophenyl esters,aryldisulfonic acid-bis-(bromophenylesters) and bis-(arylsulfonic acidesters) of brominated bisphenols, their preparation and flameproofpreparations of olefins containing these compounds as fire-retardants.

SUMMARY OF THE INVENTION

The new aryl mono- or disulfonic acid esters of highly brominatedphenols have a structure of the general formula ##STR5## wherein R¹represents hydrogen, alkyl groups of 1 to 8 carbon atoms, bromine, orchlorine, R² represents R¹ or the group ##STR6## the expression Halrepresenting bromine or chlorine, x representing the numbers 2 to 4; yrepresenting 4-x, n the numbers 3 to 5 and m representing 5-n, R³representing bromine, chlorine or the group ##STR7## and Z representing--O--, --S--, alkylene with 1 to 4 carbon atoms or alkylidene, such as--CH₂ -- or ##STR8## It is to be understood that the substituents R¹ onthe same carbon ring can be identical or different, and that in the caseof aryldisulfonic acid bis-esters, the sulfonic ester groups are not inthe ortho position.

The substances of the invention are easily accessible through thereaction of a solution of the bromophenols in their phenols form in anappropriate solvent, with arylsulfonic acid chlorides, at normal orelevated temperature.

Hitherto, the only substances having a structure corresponding toFormula I which have been described in the literature either contain nohalogen, or they contain chlorine, or else they are only weaklybrominated, so that the arylsulfonic acid esters claimed in accordancewith the invention are new substances. The following are examples ofarylsulfonic acid components for the preparation of the substances ofthe invention: benzenesulfonyl chloride, alkyl- and especiallymethylbenzenesulfonyl chlorides such as o- or p-toluenesulfonylchloride, benzene-1,3-disulfonyl chloride, chlorinated or, if desired,brominated benzenesulfonyl chlorides having 1 to 5 chlorine or bromineatoms, such as 2,3,4,5-tetrachlorobenzenesulfonyl chloride, and isomersor mixtures of isomers thereof, and similar compounds. The following canbe used as bromophenols or brominated bisphenols: 2,4,6-tribromophenol,the isomeric tetrabromophenols or isomer mixtures, pentabromophenol,brominated p,p'-diphenylolalkyldienes such as tetrabromobisphenol A;3,5,3',5'-tetrabromo-4,4'-dihydroxydiphenylsulfone, and others. Ofthese, in the case of the mononuclear bromophenols, those especially arepreferentially suitable which contain at least three bromine atoms peraromatic nucleus and, in some cases, additional chlorine atoms. Thereaction is performed with equivalent amounts, small excesses of onecomponent being possible, i.e., one mole of phenol or one-half mole ofbisphenol with each mole or arylsulfonyl chloride, and 2.0 moles ofphenol with each mole or aryldisulfonyl chloride, in which caserelatively low temperatures of 10° C. to about 80° C., and generally 20°C. to 60° C., are possible.

The solvents used need not be especially selected. Those which aremiscible or partially miscible with water are desirable, such as lowalcohols of 1 to 6 carbon atoms, glycols, and glycol ethers, and thelike.

The substances of Formula I are very effective and advantageousflameproofing agents for polyolefins, i.e., polyethylene of high or lowdensity, polypropylene, polybutylene, polymethylpentene, and others.They fulfill to a high degree the requirements which must be satisfiedby a good flameproofing agent. They can easily be incorporated intopolyolefins, they are well compatible with the polymers. They do notchalk out, and they are entirely stable thermally at the necessaryfabrication temperatures.

Another advantage of the substances of the invention is that relativelysmall amounts suffice for the achievement of good flameproofing effect,while producing only slight alterations of the physical and mechanicalproperties of the finished products.

Still another considerable advantage is that the bromine content of thesubstances of Formula I need not be too high, in contrast to numerousconventional flameproofing agents. Thus it is generally unnecessary toselect compounds in which the aromatic nucleus originating from thesulfonyl chloride is brominated, even though compounds brominated orchlorinated in this manner are entirely usable. Surprisingly, substanceshaving three bromine atoms in the aromatic nucleus of the phenolradical, i.e., those containing only 40 to about 50 wt.-% bromine,produce a good flame inhibiting action, and in some cases produce asgood a flame inhibiting action as more highly brominated compounds.Also, disulfonic acid esters of bisphenols havine four bromine atomsdivided between the two aromatic nuclei provide a good flame-inhibitingaction in spite of a bromine content of less than 40% by weight. Sincethe bromine content is a substantial factor in the cost of flameproofingagents, on account of the high cost of bromine, the comparatively lowbromine content of the substances of the invention and the simplicity oftheir production result in a technical and economic advantage.

The arylsulfonic acid esters of the present invention are used in thepolymers together with synergetically acting compounds such as zincborate, sodium antimonite, and, to special advantage, with antimonytrioxide. The synergism with antimony trioxide is no pronounced thatsurprisingly low amounts of antimony trioxide produce goodflame-inhibiting effects, making the arylsulfonic acid esters of thepresent invention superior, again, to other flame-proofing agents. Amongthe substances of the invention, the synergistic effect ofbenzenesulfonic acid tribromophenyl ester with antimony trioxide isespecially advantageous.

In general, from 2 to 15 weight-percent of the arylsulfonic acid esteris used, from 3 to 10% being especially advantageous. Of the antimonytrioxide, 0.3 to 8% is used, from 0.5 to 5 weight-percent beingespecially advantageous.

The incorporation of the flameproofing additives can be accomplished ina conventional manner by mixing on heated rollers, by mixing in anextruder, or by any other suitable method.

EXAMPLES

The following examples are intended to explain the invention and themethods of the invention, without limiting them.

The present invention is being described with reference to certainspecific embodiments, and it is to be observed that modifications andvariations can be made within the scope of the claims that follow. Theinvention can also be embodied in a technically different manner thandescribed herein, without departing from the scope of the invention orfrom the idea thereof.

EXAMPLE 1--Preparation of benzenesulfonic acid-2,4,6-tribromophenylester (a) In ethanol as solvent

In a two-liter reaction flask equipped with stirrer, dropping funnel andthermometer, 800 ml of 90% aqueous ethyl alcohol and 496.5 g (1.5 moles)of technical 2,4,6-tribromophenol were placed and mixed by stirring atroom temperature with a solution of 60 g (1.5 moles) of sodium hydroxidein 60 ml of water, whereupon the tribromophenol went rapidly intosolution with the formation of phenolate, and the mixture warmed ofitself to about 32°-35° C.

The brownish phenolate solution obtained was cooled down to about 25°C., and then, with stirring, 265 g, equal to approximately 192 ml (1.5moles) of benzenesulfonic acid chloride was added drop by drop over aperiod of 40 to 60 minutes such that the temperature of the mixture didnot rise above 35° C.

The arylsulfonic acid ester precipitated soon in colorless needles inaddition to sodium chloride.

After all of the sulfonyl chloride had been added, the mixture wasstirred at about 30° C. for one hour, and then it was cooled to roomtemperature and the solids were removed with a suction filter. Thefilter cake was first washed with a little ethanol, and then the sodiumchloride was washed out with water until there was no longer anychloride in the filtrate, and the ester was then dried. 638 g ofarylsulfonic acid ester was obtained, corresponding to a yield of 90.5%.Melting point 82°-86° C.

(b) In ethylene glycol monomethyl ether (methyl cellosolve)

As under (a), in a similarly equipped 4-liter flask, 1,986 g (6 moles)of tribromophenol was suspended in 3.2 liters of water-containing methylcellosolve (B.P. 117°-122° C.) and dissolved to form the phenolate byadding a solution of 240 g (6 moles) of sodium hydroxide in 240 ml ofwater.

Then, at a temperature between 25° and 35° C., 1,060 g=768 ml (6 moles)of benzenesulfonyl chloride was stirred, drop by drop, into thephenolate solution. Sodium chloride and the sulfonic acid ester began toprecipitate after the addition of about a third of the sulfonic acidchloride.

After all of the benzenesulfonyl chloride had been added, the reactionwas completed at 35° C. in one hour, and then the crystalline mass waschilled to about 0° C., and the ester and sodium chloride were removedwith a suction filter. The filter cake was stirred in 8 liters of water,the ester was suction filtered and washed free of sodium chloride. Thenit was vacuum-dried at 50°-60° C.

2,665 g, corresponding to a 94.3% yield, of colorless needles melting at83.5°-84.5° C. was obtained.

10 g of the raw ester was recrystallized from 30 ml of cyclohexane, orethanol, or isopropanol. 8.7 g was obtained, having a melting point of84.5°-86° C.

Elemental analysis: C₁₂ H₇ Br₃ O₃ S (Mol. Wt. 470.98). Calculated: C30.6%; H 1.5%; Br 50.95%; O 10.2%; S 6.8%. Found: C 30.49%; H 1.42%; Br51.11%; O 10.32%; S 6.76%.

EXAMPLE 2--Preparation of pentabromophenylbenzenesulfonic acid ester

In the same apparatus as in Example 1, 488.7 g (1 mole) ofpentabromophenol was suspended in 1.5 liters of methylcellosolve (B.P.117°-122° C.), and was transformed to the phenolate by stirring into ita solution of 40 g (1 mole) of sodium hydroxide in 40 ml of water. Tothis phenolate solution, 177 g=128 ml (1 mole) of technicalbenzenesulfonic acid chloride was added drop by drop in such a mannerthat the temperature of the reaction mixture did not rise above 35°-37°C.

The ester that formed began to precipitate together with sodium chlorideafter about half of the sulfonyl chloride had been added. After all ofthe benzenesulfochloride had been added, stirring was continued for 1hour at 35° C. and the suspension was then cooled to room temperature.

The solids were suction filtered as in Example 1 and washed free ofsodium chloride. After drying, we obtained 577 g, corresponding to 91.8%of the theoretically possible quantity of virtually colorlessbenzenesulfonic acid ester melting at 158°-160° C. (a residue at170°-172° C.).

30 g of raw ester was recrystallized from benzene in a ratio of 1:4, orfrom xylene 1:4, or even methoxyethyl chloride 1:4, and colorlesscrystals melting at 171°-173° C. were thus obtained. 20 g of thisproduct was once again recrystallized from 150 ml of a 1:1 mixture ofcyclohexane and benzene, and yielded 14.9 g of pure crystallizate of amelting point of 172°-174° C.

Elemental analysis: C₁₂ H₅ Br₅ O₃ S (Mol. wt. 628.8). Calc.: C 22.92%; H0.80%; Br 63.54%; O 7.63%; S 5.10%. Found: C 23.11%; H 0.74%; Br 63.43%;O 7.63%; S 4.96%.

EXAMPLE 3--Preparation of a benzenesulfonic acid ester from abromophenol containing chlorine in the nucleus

For this experiment a halogen phenol mixture was used which had beenobtained by the bromination of phenol with bromine chloride, and had thefollowing gross composition: ##STR9## Bromine content: 67.5% Chlorinecontent: 11.0%

By the procedure of Example 1, 123 g (about 0.3 moles) of halogen phenolof the above composition was suspended in 450 ml of ethyleneglycolmonomethyl ether (B.P. 116°-121° C.) and dissolved to the phenolate bythe addition of 12 g of sodium hydroxide in 12 ml of water.

At 30° C., it was then reacted to form the ester by adding, drop bydrop, 53 g=38.4 ml (0.3 moles) of benzenesulfonyl chloride, theesterification being completed by allowing the reaction to continue for45 minutes at 30° C.

After the precipitated material had been processed as described above,we obtained 153 g (98.5% yield) of benzenesulfonic acid halophenylester, M.P. 152°-154° C.

10 g of the raw ester, recrystallized from 60 ml of cyclohexane andbenzene in a ratio of 2:1 by volume, yielded 9.3 g of colorlesscrystallizate of the same melting point of 152°-154° C.

In the same manner, by the reaction of a variously substitutedhalophenol of the gross composition C₆ H_(y) Hal_(x) --OH, whereiny=0.56, Hal_(x) =Br₄.33 +Cl₀.11, with benzene-sulfonic acid chloride,the corresponding benzenesulfonic acid halophenyl ester was obtained ina 91% yield.

Elemental composition: C₆ H₅ SO₂ O C₆ H₀.56 Br₄.33 Cl₀.11

EXAMPLE 4--Preparation of p-toluenesulfonic acid pentabromophenyl ester

In a one-liter three-necked flask equipped with stirrer and thermometer,there was placed 600 ml of methyl cellosolve (B.P. 117°-122° C.), and345 g (0.5 moles) of pentabromophenol was suspended therein anddissolved to the phenolate by stirring in 20 g (0.5 moles) of sodiumhydroxide dissolved in 20 ml of water.

At about 40° C., 95.4 g (0.5 moles) of p-toluenesulfonyl chloride insolid form was added in portions with vigorous stirring. Stirring wasthen continued for 1 hour at 40° C. and then, after cooling to roomtemperature, the precipitated solids were isolated as in Example 2.

We obtained 306 g (95.3% yield) of light brown raw ester melting at192°-198° C. 15 g of raw ester, upon recrystallization from toluene in aratio of 1:4 with the addition of animal charcoal, yielded 12 g ofcolorless crystallizate melting at 197.5°-200° C.

Elemental Analysis: C₁₃ H₇ Br₅ O₃ S (Mol. wt. 642.8). Calc.: C 24.29%; H1.10%; Br 62.16%; O 7.47%; S 4.99%. Found: C 24.38%; H 0.98%; Br 62.35%;O 7.36%; S 4.78%.

The o-toluenesulfonic acid pentabromophenyl ester can be prepared in thesame manner by using the same molar amount of o-toluenesulfonyl chlorideinstead of the para compound.

EXAMPLE 5--p-Toluenesulfonic acid-2,4,6-tribromophenyl ester

This ester was prepared similarly to the preceding examples with thefollowing quantities:

300 ml of methylcellosolve (B.P. 117°-122° C.)

165.5 g (0.5 mole) of 2,4,6-tribromophenol,

20 g (0.5 mole) of sodium hydroxide in 20 ml water,

95.4 g (0.5 mole) of p-toluenesulfonyl chloride.

Raw ester yield: 221 g, corresponding to 91%. Melting point: 112°-113.5°C. After recrystallization from cyclohexane in a ratio of 1 g of esterto 6 ml of solvent, the melting point was 113°-114.5° C.

Elemental analysis: C₁₃ H₉ Br₃ O₃ S (mol. wt. 485.06). Calc.: C 32.22%;H 1.86%; Br 49.40%; O 9.90%; S 6.62%. Found: C 32.38%; H 1.73%; Br49.63%; O 9.98%; S 6.71%.

In the same manner the o-toluenesulfonic acid-2,4,6-tribromophenyl estercan be obtained by using o-toluenesulfonyl chloride in the same molaramount instead of the para compound.

EXAMPLE 6--2,3,4,5-tetrachlorobenzenesulfonic acid-2,4,6-tribromophenylester ##STR10##

In preparing this sulfonic acid ester a sulfonyl chloride was used whichhad been obtained by the reaction of chlorosulfonic acid with "tetraoil", a by-product occurring in the production of hexachlorocyclohexane.

Tetra oil is a mixture of chlorinated benzenes, and it is composed asfollows:

0.4% 1,2,3-trichlorobenzene

8.3% 1,2,4-trichlorobenzene

13.9% 1,2,4,5-tetrachlorobenzene

65.1% 1,2,3,4-tetrachlorobenzene, and

12.3% pentachlorobenzene.

By fractional distillation we obtained the 1,2,3,4-tetrachlorobenzene ina purity of about 95%, and from that we obtained the sulfochloride witha melting point of about 70° C. in a 76% yield.

In the apparatus already described, 82.7 g (0.25 mole) of technical2,4,6-tribromophenol was suspended in 250 ml of methyl glycol (B.P.122°-126° C.) and converted to the phenolate with a lye prepared from 10g (0.25 mole) of sodium hydroxide in 10 ml of water. At 35° C., 78.6 g(0.25 mole) of 2,3,4,5-tetrachlorobenzenesulfonyl chloride was thenstirred in portion-wise such that the temperature in the reactionmixture did not exceed 40° C. A fine, white precipitate formed.

We let the reaction continue for one hour at 60° C., and then cooled themixture to room temperature and removed the precipitate with a suctionfilter. The precipitate was washed chloride-free with water and dried.

Yield: 128 g (84%) M.P. 162°-166° C.

10 grams, when recrystallized from 50 ml of methyl-cellosolve, had amelting point of 164°-167° C. Repeated recrystallization did not changethe melting point.

Elemental analysis: C₁₂ H₃ Br₃ Cl₄ O₃ S (mol. wt. 308.76). Calc.: C23.69%; H 0.50%; Br 39.38%; Cl 23.29%; O 7.88%; S 5.26%. Found: C23.83%; H 0.46%; Br 39.50%; Cl 23.16%; O 8.01%; S 5.34%.

EXAMPLE 7--m-Benzenedisulfonic acid-bis-(2,4,6-tribromophenyl ester)

By the procedure described above, 331 g (1.0 mole) of tribromophenol wassuspended cold in 500 ml of methyl glycol having a boiling point of117°-122° C., and converted to the phenolate by the addition of asolution of 40 g (1.0 mole) of sodium hydroxide in 40 ml of water.

A solution of 138 g (0.5 mole) of technical benzene-1,3-disulfochloride,dissolved in 350 ml of methyl glycol, was added drop by drop to thephenolate solution, whereupon a white precipitate immediately formed. Athickish suspension formed, which, after the addition of all of thesulfochloride, was stirred for another hour at 40° C.

After the mixture had cooled to room temperature, the precipitate wassuction filtered, washed free of sodium chloride, and dried.

Yield: 358 g (83%) of raw, colorless disulfonic acid ester melting at163° to 168° C.

After two recrystallizations of 20 grams from 200 ml of a mixture ofbenzene and cyclohexane in a ratio of 3:2 by volume, the melting pointwas 172°-175° C.

Elemental analysis: C₁₈ H₈ Br₆ O₆ S₂ (mol. wt. 863.84). Calculated: C25.03%; H 0.93%; Br 55.50%; O 11.11%; S 7.42%. Found: C 25.14%; H 0.91%;Br 55.32%; O 11.23%; S 7.31%.

EXAMPLE 8--m-Benzenedisulfonic acid-bis-(pentabromophenyl ester)

By the same procedure as in Example 7,

50 ml of methylcellosolve,

48.9 g (0.1 mole) of pentabromophenol,

4.0 g (0.1 mole) of sodium hydroxide, dissolved in 4 ml of water, and

13.8 g (0.05 mole) of benzene-1,3-disulfonylchloride,

dissolved cold in 50 ml of methylcellosolve, was brought to reaction,the solution of the disulfonyl chloride being added drop by drop to thephenolate solution, with stirring, over a period of about 20 minutes at30° C. The stirring was then continued for an additional hour at 30° C.

After the mixture had cooled to room temperature, the suspension wassuction filtered and the bis-ester was washed free of sodium chloridewith water. After drying we obtained 52.5 g (89% yield) melting at248°-255° C.

10 g of the raw ester was recrystallized from 100 ml of xylene. Weobtained a colorless crystallizate melting at 253°-256° C. The substanceis furthermore soluble in dioxane and o-dichlorobenzene, for example.

Elemental analysis: C₁₈ H₄ Br₁₀ O₆ S₂ (mol. wt. 1,179.45). Calc.: C18.33%; H 0.34%; Br 67.75%; O 8.14%; S 5.44%. Found: C 18.46%; H 0.31%;Br 67.62%; O 7.99%; S 5.47%.

EXAMPLE 9--Preparation of tetrabromobisphenol-A-bis(benzenesulfonic acidester) ##STR11## (a) In water

As described in the preceding examples, 2.040 g (3.75 moles) oftechnical tetrabromobisphenol A (i.e.,3,5,3',5'-tetrabromo-4,4'-dihydroxy-2,2-diphenylpropane) was suspendedin 6 liters of water and dissolved to form the phenolate in a solutionof 300 g (7.5 moles) of sodium hydroxide in 300 ml of water. At 25° C.,1,325 g=960 ml (7.5 moles) of benzenesulfonyl chloride was added to thissolution drop by drop, with vigorous stirring, the ester settling outimmediately as a colorless precipitate. After all of the benzenesulfonylchloride had been added, we continued stirring for 30 minutes at roomtemperature. The ester was then suction filtered, washed free ofchloride and dried. 2,850 g (92.2% yield) melting at 196°-205° C. wasobtained.

(b) In methylcellosolve

In the manner described under (a), the following were reacted at 40° C.and processed as described:

2,040 g (3.75 moles) of tetrabromo-bisphenol A,

6 liters of methylcellosolve (B.P. 116°-121° C.),

300 g (7.5 moles) of NaOH in 300 ml of water, and

1,325 g=960 ml (7.5 moles) of benzenesulfonyl chloride. 2,996 g (96.9%)of raw ester was obtained, M.P. 196.5°-204° C. 20 g of the raw ester wasrecrystallized from 200 ml of a mixture of xylene and cyclohexane in aratio of 3:2 by volume, yielding a colorless crystallizate melting at204°-206° C.

Elemental analysis: C₂₇ H₂₀ Br₄ O₆ S₂ (mol.wt. 824.22). Calc.: C 39.35%;H 2.45%; Br 38.78%; O 11.65%; S 7.78%. Found: C 39.41%; H 2.34%; Br38.91%; O 11.50%; S 7.66%.

In like manner, the tetrabromobisphenol-A-bis-(o-toluenesulfonic acidester) and the -bis-(p-toluenesulfonic acid ester) are obtained byreacting o- and p-toluenesulfonic acid chloride, respectively, insteadof benzenesulfonic acid chloride, with the bisphenol.

EXAMPLE 10--Preparation of3,5,3',5'-tetrabromo-4,4'-dihydroxydiphenylsulfone-bis-(benzenesulfonate) ##STR12##

In the manner described in the preceding examples, the following werereacted

141.5 g (0.25 moles) of tetrabromodihydroxydiphenylsulfone, M.P.285°-292° C.

1 liter of methylcellosolve

20 g (0.5 mole) of NaOH in 20 ml of water, and

88.3 g=64 ml (0.5 mole) of benzenesulfonyl chloride.

The benzenesulfonic acid chloride was added drop by drop over a periodof 15 minutes at 30° C. The mixture was worked up as repeatedlydescribed in the previous examples.

We obtained 176 g of raw ester, corresponding to a yield of 83%. Themelting point was found at 184°-188° C. Upon recrystallization fromxylene 1:6 we obtained colorless needles melting at 187°-190° C.

Elemental analysis: C₂₄ H₁₄ Br₄ O₈ S₃ (mol. wt. 846-21). Calc.: C34.07%; H 1.67%; Br 37.77%; O 15.13%; S 11.37%. Found: C 34.18%; H1.53%; Br 37.59%; O 15.04%; S 11.42%.

EXAMPLE 11--Preparation of3,5,3',5'-tetrabromo-4,4'-dihydroxy-2,2-diphenylpropane-bis-(2,3,4,5-tetrachlorobenzenesulfonate) ##STR13##

By the same procedure as already described, 108.8 g (0.2 mole) oftechnical tetrabromobisphenol A was suspended cold in 600 ml ofmethylcellosolve and dissolved to the phenolate by the addition of 16 g(0.4 mole) of sodium hydroxide in 16 ml of water. 125.8 g (0.4 mole) oftetrachlorobenzenesulfonyl chloride--prepared as in Example 6--wasstirred into this solution at 40° C., and this reaction mixture wasreacted three hours at 70° C. with stirring. Then the suspension thathad been formed was cooled to room temperature and worked up aspreviously described.

We obtained 191 g (87%) of raw ester, M.P. 214°-240° C. Afterrecrystallization 1:24 from ethylene glycol-monobutyl ether, M.P.241°-247°.

Elemental analysis: C₂₇ H₁₂ Br₄ Cl₈ O₆ S₂ (mol. wt. 1,099.8). Calc.: C29.49%; H 1.10%; Br 29.06%; Cl 25.79%; O 8.73%; S 5.92%. Found: C29.61%; H 1.04%; Br 29.18%; Cl 25.59%; O 8.66%; S 5.81%.

EXAMPLE 12

This example demonstrates the use of the compounds of the presentinvention as flameproofing agents for polyolefins.

The good thermal stability of the substances of the invention isapparent, for example, from the values obtained in the thermoanalyticdetermination of weight losses. The following, for example, wereobtained with the benzenesulfonic acid esters of the tribromophenol fromExample 1, in air, at a warming rate of 8° C. per minute:

    ______________________________________                                        Weight Losses                                                                 ______________________________________                                        1% at 256° C.                                                                      5% at 282° C.                                                                         10% at 290°C.                               ______________________________________                                    

With the substance of Example 9, we found the following:

    ______________________________________                                        Weight Losses                                                                 ______________________________________                                        1% at 281° C.                                                                      5% at 293° C.                                                                         10% at 301° C.                              ______________________________________                                    

The following table shows the test results for the degree of flameresistance based on the oxygen index testing of numerous samplescontaining various substances of the invention.

The values given under LOI vol.-% O₂ were determined in accordance withASTM D 2863-70. They refer to the concentration of oxygen, expressed involume-percent of an oxygen-nitrogen mixture which can barely sustainthe combustion of the sample under the conditions of the experiment. Thegreater the oxygen index is, the better is the flame-inhibiting actionof the formulation.

The incorporation of the flameproofing agents into the polyolefins wasperformed in a roller mixer. The roller skins obtained were then pressedto form the test strips.

                                      TABLE                                       __________________________________________________________________________    per 100 grams of polyolefin. PA = polyethylene PP = polypropylene                          Substance                                                                            Amount of the flame                                                    of     proofing agent                                                                            LOI                                           Mixture                                                                              Polyolefin                                                                          Example No.                                                                          Ester Sb.sub.2 O.sub.3                                                                    Vol % O.sub.2                                 __________________________________________________________________________    Example or                                                                           PA    --     --    --    10.5                                          Comparison                                                                    Example or   octabromo-                                                       Comparison                                                                           PA    diphenyl                                                                             9 g   4 g   27.2                                                       ether                                                            1      PA    1      12 g  5 g   30.3                                          2      PA    1      12 g  2 g   29.6                                          3      PA    1      9 g   3 g   27.7                                          4      PA    1      9 g   4 g   27.6                                          5      PA    1      9 g   3 g   28.6                                          6      PA    1      9 g   2 g   28.3                                          7      PA    1      9 g   1 g   27.2                                          8      PA    1      9 g   --    19.4                                          9      PA    1      6 g   3 g   27.4                                          10     PA    1      6 g   2 g   27.2                                          11     PA    1      3 g   2 g   21.8                                          12     PP    --     --    --    17.3                                          13     PP    1      12 g  6 g   27.3                                          14     PP    1      12 g  4 g   26.6                                          15     PP    1      12 g  2 g   25.1                                          16     PP    1      9 g   4 g   25.5                                          17     PP    1      9 g   3 g   25.1                                          18     PP    1      9 g   2 g   24.5                                          19     PP    1      6 g   3 g   24.5                                          20     PP    1      6 g   2 g   24.1                                          21     PA    2      12 g  6 g   28.3                                          22     PA    2      12 g  5 g   28.0                                          23     PA    2      12 g  4 g   27.9                                          24     PA    2      12 g  2 g   27.7                                          25     PA    2      9 g   4 g   25.8                                          26     PA    3      12 g  5 g   39.0                                          27     PA    3      12 g  2 g   29.3                                          28     PA    4      12 g  5 g   29.4                                          29     PA    4      12 g  4 g   29.4                                          30     PA    4      12 g  2 g   29.0                                          31     PA    4      9 g   4 g   29.5                                          32     PA    4      9 g   2 g   28.8                                          33     PA    4      9 g   --    19.3                                          34     PA    4      6 g   4 g   27.7                                          35     PA    4      6 g   2 g   27.2                                          36     PA    6      12 g  6 g   27.6                                          37     PA    6      12 g  4 g   27.2                                          38     PA    6      12 g  2 g   26.9                                          39     PA    6      9 g   4 g   26.5                                          40     PA    6      9 g   3 g   26.4                                          41     PA    6      9 g   2 g   26.2                                          42     PA    6      6 g   3 g   23.6                                          43     PA    6      6 g   2 g   23.4                                          44     PA    7      12 g  6 g   29.7                                          45     PA    7      9 g   4 g   27.8                                          46     PA    7      9 g   2 g   26.4                                          47     PA    8      12 g  5 g   28.7                                          48     PA    8      9 g   4 g   27.2                                          49     PA    8      9 g   2 g   26.4                                          50     PA    9      12 g  6 g   29.5                                          51     PA    9      12 g  4 g   30.1                                          52     PA    9      12 g  2 g   29.8                                          53     PA    9      9 g   4 g   29.5                                          54     PA    9      9 g   3 g   29.1                                          55     PA    9      9 g   2 g   28.6                                          56     PA    9      6 g   3 g   27.6                                          57     PA    9      6 g   2 g   26.9                                          Example      Octabromo-                                                       or     PA    diphenyl                                                                             12 g  4 g   27.3                                          Comparison   ether                                                            Example or                                                                           PA    Octabromo-                                                       Comparison   diphenyl                                                                             12 g  2 g   26.4                                                       ether                                                            Example or                                                                           PA    Octabromo-                                                       Comparison   diphenyl                                                                             9 g   4 g   27.3                                                       ether                                                            Example or                                                                           PA    Octabromo-                                                       Comparison   diphenyl                                                                             9 g   2 g   26.3                                                       ether                                                            Example or                                                                           PA    Octabromo-                                                       Comparison   diphenyl                                                                             6 g   4 g   26.9                                                       ether                                                            Example or                                                                           PA    Octabromo-                                                       Comparison   diphenyl                                                                             6 g   2 g   26.0                                                       ether                                                            __________________________________________________________________________

The table clearly shows the superiority of the action of the substancesof the present invention in comparison with common commercialflameproofing agents. In the specimens containing the new substancesthere are many oxygen index values above about 27, which cannot beachieved at all with many of the prior-art substances, or only by theincorporation of amounts which impair the characteristics of thepolyolefins. It is remarkable that good results are obtained withsamples of the substance of Example 1 containing only three bromineatoms per molecule; also noteworthy is the particularly strong synergismof the Sb₂ O₃ and the good oxygen index obtainable in this case withsmall contents of Sb₂ O₃. Especially mixtures Nos. 5, 6 and 52 show thepronounced synergism with antimony trioxide, the amount of which can besurprisingly small. How conspicuous this synergism is is shown byMixtures Nos. 8 and 33, which were prepared without Sb₂ O₃.

We claim:
 1. Aryl disulfonic acid esters of polybrominated phenols ofthe general formula ##STR14## wherein R¹ represents hydrogen, alkylgroups of 1 to 8 carbon atoms, bromine or chlorine,R² represents R¹ orthe group ##STR15## Hal represents bromine or chlorine, x the number 2to 4, n the numbers 3 to 5, y the numbers 4-x, m=5-n, R³ represents thegroup ##STR16## and Z represents --O--, --S--, ##STR17## alkylene with 1to 4 carbon atoms, or alkylidene.
 2. An aryl disulfonic acid esteraccording to claim 1 wherein Z represents alkylene with 1 to 4 carbonatoms or alkylidene.
 3. m-Benzenedisulfonic acidbis-(2,4,6-tribromophenyl ester.
 4. m-Benzenedisulfonic acidbis-(pentabromophenyl ester.
 5. Tetrabromobisphenol Abis-(benzenesulfonic acid ester).
 6. Tetrabromobisphenol A bis-(o-and/or p-toluenesulfonic acid ester). 7.3,5,3',5'-Tetrabromo-4,4'-dihydroxydiphenylsulfone bis-(benzenesulfonicacid ester).
 8. Tetrabromobisphenol Abis-(2,3,4,5-tetrachlorobenzenesulfonic acid ester).
 9. An arylsulfonicacid ester according to claim 1 wherein R² is hydrogen, a C₁₋₈ alkylgroup, bromine or chlorine.
 10. An arylsulfonic acid ester according toclaim 1 wherein R² is a group ##STR18## wherein Hal is bromine orchlorine, n is a number of 3 to 5 and m is (5-n).